1. Field of the Invention
This invention is related to a machine and its method of operation for the production of float flat glass by the floating process, and more specifically to a system to automatically lift the outlet curtains of the exit hood of the machine, operate the reheating system of the floating chamber, retract the glass edge follower mechanism of the glass ribbon, and trigger the alarm of the glass forming machine, so as to allow for the rapid restoration of the glass ribbon forming process.
2. Description of the Related Art
At the outlet of the floating chamber of the typical machine for producing float flat glass by the floating process, there is a series of curtains within the equipment. This part of the equipment, known as the "exit hood", act as gates to avoid heat loss from the exit hood and floating chamber.
The height of these curtains is commonly adjusted by a manually operated mechanical positioning system. The curtains can be lifted to their maximum height in the case of an emergency, usually by a pneumatic motor, coupled to the positioning system.
In the case of a control failure in the glass ribbon forming process, which normally results in a breakage of the glass ribbon, it is necessary that an operator at the forming zone, trigger the alarm of the machine and rapidly lift the curtains to their maximum height using the pneumatic system. This is necessary to avoid the broken glass ribbon from clogging the curtains. Thus, it is absolutely necessary to have an operator continuously inspecting this zone of the forming process.
Other components of the machine, such as the reheating system of the glass chamber which compensates for thermal looses at the curtains, and the glass edge follower mechanism which helps in guiding the glass ribbon and which has to be withdrawn in case of a breakage to avoid the broken glass from clogging at the curtains, among others, also have to be controlled in case of a breakage of the glass ribbon. The controls should also allow a rapid restoration and continuation of the forming process without inconvenient loss of time, energy and materials.
If the operator takes such emergency actions in a minimum of time, the process can be rapidly restored. Otherwise, the broken glass ribbon will obstruct the outlet at the curtains and will cause an interruption of the forming process with the consequent loss of material and thermal equilibrium.
According to the present invention, the curtains are automatically lifted immediately upon breakage of the glass ribbon, and other actions are taken to avoid undesirable interruptions of the process. This system has been developed after research to find a solution that does not depend on the operator's awareness of the problem and response time. Hence, applicants have invented a system which automatically and immediately takes such actions upon detecting such glass breaking.
The detection of a breaking of the glass ribbon, is carried out, in accordance with the present invention, by the incidence of a light beam on the glass surface. The reflected light beam, provides a signal representative of the absence or deviation of the light beam because of a breakage of the glass ribbon. This signal is fed to a data processor which, upon receiving the signal representative of the absence of the light beam, provides operating signals to actuators to operate i) the curtain lifting mechanism, ii) the reheating system of the glass chamber (to keep a thermal equilibrium), iii) the glass edge follower mechanism (to retract it and avoid clogging), and iv) to trigger the alarm of the machine, to carry out other necessary control operations to allow for a rapid restoration of the process.
Some advantages of the system of the present invention as described above, are that the system will automatically and immediately carry out the necessary steps to avoid clogging of the broken glass ribbon at the curtains and other components at the floating chamber, without depending on the human operator's recognition of the problem and of the time for the operator's response to an urgent solution.
Consequently, other advantages of the present invention are that the system will save energy and material by restoring the normal process conditions in a minimum time, to continue the glass ribbon forming process.
An apparatus is presently known for detecting the presence of a mark (usually a trademark) on a transparent substrate. This apparatus, as disclosed in Koontz, U.S. Pat. No. 4,665,392, includes a light beam emitter to provide a light beam through the upper surface of the transparent substrate. The light beam is received by a detector on the opposite face of the substrate to provide a signal representative of the mark on the substrate to take the necessary steps in an application station for printing such marks. However, this apparatus is absolutely different from the system herein disclosed. This is for an entirely different purpose and operated under different concepts as the system of the present invention.